Optical finger navigation devices use a light source to illuminate a user's finger and a sensor array to generate digital images from light that is reflected off of the user's finger. Successive digital images are compared to each other to compute movement information. Typical optical finger navigation systems output two-dimensional movement information that represents the two-dimensional movement of the finger relative to the sensor array. The two-dimensional movement information is then used to move a cursor on a display of a corresponding computing device.
While optical finger navigation devices can be used to move a cursor on a display, the graphical user interface of many computing devices, such as personal computers, telephones, smart phones, and personal digital assistants (PDAs), require functionality other than cursor movement. For example, many graphical user interfaces require scrolling functionality or four-way rocker functionality. Scrolling functionality is commonly provided using a mechanical scroll and/or tilt wheel and four-way rocker functionality is commonly provided using a mechanical four-way rocker with activation switches at four distinct locations.
While optical finger navigation devices can support two-dimensional navigation of a cursor within a graphical user interface, there is a need for optical finger navigation devices to support the scrolling and four-way rocker functionality that is commonly provided by mechanical scroll wheels and four-way rockers.